const {
  AnimationClip,
  Bone,
  Box3,
  BufferAttribute,
  BufferGeometry,
  ClampToEdgeWrapping,
  Color,
  DirectionalLight,
  DoubleSide,
  FileLoader,
  FrontSide,
  Group,
  ImageBitmapLoader,
  InstancedMesh,
  InterleavedBuffer,
  InterleavedBufferAttribute,
  Interpolant,
  InterpolateDiscrete,
  InterpolateLinear,
  Line,
  LineBasicMaterial,
  LineLoop,
  LineSegments,
  LinearFilter,
  LinearMipmapLinearFilter,
  LinearMipmapNearestFilter,
  Loader,
  LoaderUtils,
  Material,
  MathUtils,
  Matrix4,
  Mesh,
  MeshBasicMaterial,
  MeshPhysicalMaterial,
  MeshStandardMaterial,
  MirroredRepeatWrapping,
  NearestFilter,
  NearestMipmapLinearFilter,
  NearestMipmapNearestFilter,
  NumberKeyframeTrack,
  Object3D,
  OrthographicCamera,
  PerspectiveCamera,
  PointLight,
  Points,
  PointsMaterial,
  PropertyBinding,
  Quaternion,
  QuaternionKeyframeTrack,
  RepeatWrapping,
  Skeleton,
  SkinnedMesh,
  Sphere,
  SpotLight,
  Texture,
  TextureLoader,
  TriangleFanDrawMode,
  TriangleStripDrawMode,
  Vector2,
  Vector3,
  VectorKeyframeTrack,
  sRGBEncoding,
} = THREE;

class GLTFLoader extends Loader {
  constructor(manager) {
    super(manager);

    this.dracoLoader = null;
    this.ktx2Loader = null;
    this.meshoptDecoder = null;

    this.pluginCallbacks = [];

    this.register(function (parser) {
      return new GLTFMaterialsClearcoatExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFTextureBasisUExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFTextureWebPExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFMaterialsSheenExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFMaterialsTransmissionExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFMaterialsVolumeExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFMaterialsIorExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFMaterialsEmissiveStrengthExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFMaterialsSpecularExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFMaterialsIridescenceExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFLightsExtension(parser);
    });

    this.register(function (parser) {
      return new GLTFMeshoptCompression(parser);
    });

    this.register(function (parser) {
      return new GLTFMeshGpuInstancing(parser);
    });
  }

  load(url, onLoad, onProgress, onError) {
    const scope = this;

    let resourcePath;

    if (this.resourcePath !== "") {
      resourcePath = this.resourcePath;
    } else if (this.path !== "") {
      resourcePath = this.path;
    } else {
      resourcePath = LoaderUtils.extractUrlBase(url);
    }

    // Tells the LoadingManager to track an extra item, which resolves after
    // the model is fully loaded. This means the count of items loaded will
    // be incorrect, but ensures manager.onLoad() does not fire early.
    this.manager.itemStart(url);

    const _onError = function (e) {
      if (onError) {
        onError(e);
      } else {
        console.error(e);
      }

      scope.manager.itemError(url);
      scope.manager.itemEnd(url);
    };

    const loader = new FileLoader(this.manager);

    loader.setPath(this.path);
    loader.setResponseType("arraybuffer");
    loader.setRequestHeader(this.requestHeader);
    loader.setWithCredentials(this.withCredentials);

    loader.load(
      url,
      function (data) {
        try {
          scope.parse(
            data,
            resourcePath,
            function (gltf) {
              onLoad(gltf);

              scope.manager.itemEnd(url);
            },
            _onError
          );
        } catch (e) {
          _onError(e);
        }
      },
      onProgress,
      _onError
    );
  }

  setDRACOLoader(dracoLoader) {
    this.dracoLoader = dracoLoader;
    return this;
  }

  setDDSLoader() {
    throw new Error(
      'THREE.GLTFLoader: "MSFT_texture_dds" no longer supported. Please update to "KHR_texture_basisu".'
    );
  }

  setKTX2Loader(ktx2Loader) {
    this.ktx2Loader = ktx2Loader;
    return this;
  }

  setMeshoptDecoder(meshoptDecoder) {
    this.meshoptDecoder = meshoptDecoder;
    return this;
  }

  register(callback) {
    if (this.pluginCallbacks.indexOf(callback) === -1) {
      this.pluginCallbacks.push(callback);
    }

    return this;
  }

  unregister(callback) {
    if (this.pluginCallbacks.indexOf(callback) !== -1) {
      this.pluginCallbacks.splice(this.pluginCallbacks.indexOf(callback), 1);
    }

    return this;
  }

  parse(data, path, onLoad, onError) {
    let json;
    const extensions = {};
    const plugins = {};

    if (typeof data === "string") {
      json = JSON.parse(data);
    } else if (data instanceof ArrayBuffer) {
      const magic = LoaderUtils.decodeText(new Uint8Array(data, 0, 4));

      if (magic === BINARY_EXTENSION_HEADER_MAGIC) {
        try {
          extensions[EXTENSIONS.KHR_BINARY_GLTF] = new GLTFBinaryExtension(
            data
          );
        } catch (error) {
          if (onError) onError(error);
          return;
        }

        json = JSON.parse(extensions[EXTENSIONS.KHR_BINARY_GLTF].content);
      } else {
        json = JSON.parse(LoaderUtils.decodeText(new Uint8Array(data)));
      }
    } else {
      json = data;
    }

    if (json.asset === undefined || json.asset.version[0] < 2) {
      if (onError)
        onError(
          new Error(
            "THREE.GLTFLoader: Unsupported asset. glTF versions >=2.0 are supported."
          )
        );
      return;
    }

    const parser = new GLTFParser(json, {
      path: path || this.resourcePath || "",
      crossOrigin: this.crossOrigin,
      requestHeader: this.requestHeader,
      manager: this.manager,
      ktx2Loader: this.ktx2Loader,
      meshoptDecoder: this.meshoptDecoder,
    });

    parser.fileLoader.setRequestHeader(this.requestHeader);

    for (let i = 0; i < this.pluginCallbacks.length; i++) {
      const plugin = this.pluginCallbacks[i](parser);
      plugins[plugin.name] = plugin;

      // Workaround to avoid determining as unknown extension
      // in addUnknownExtensionsToUserData().
      // Remove this workaround if we move all the existing
      // extension handlers to plugin system
      extensions[plugin.name] = true;
    }

    if (json.extensionsUsed) {
      for (let i = 0; i < json.extensionsUsed.length; ++i) {
        const extensionName = json.extensionsUsed[i];
        const extensionsRequired = json.extensionsRequired || [];

        switch (extensionName) {
          case EXTENSIONS.KHR_MATERIALS_UNLIT:
            extensions[extensionName] = new GLTFMaterialsUnlitExtension();
            break;

          case EXTENSIONS.KHR_DRACO_MESH_COMPRESSION:
            extensions[extensionName] = new GLTFDracoMeshCompressionExtension(
              json,
              this.dracoLoader
            );
            break;

          case EXTENSIONS.KHR_TEXTURE_TRANSFORM:
            extensions[extensionName] = new GLTFTextureTransformExtension();
            break;

          case EXTENSIONS.KHR_MESH_QUANTIZATION:
            extensions[extensionName] = new GLTFMeshQuantizationExtension();
            break;

          default:
            if (
              extensionsRequired.indexOf(extensionName) >= 0 &&
              plugins[extensionName] === undefined
            ) {
              console.warn(
                'THREE.GLTFLoader: Unknown extension "' + extensionName + '".'
              );
            }
        }
      }
    }

    parser.setExtensions(extensions);
    parser.setPlugins(plugins);
    parser.parse(onLoad, onError);
  }

  parseAsync(data, path) {
    const scope = this;

    return new Promise(function (resolve, reject) {
      scope.parse(data, path, resolve, reject);
    });
  }
}

/* GLTFREGISTRY */

function GLTFRegistry() {
  let objects = {};

  return {
    get: function (key) {
      return objects[key];
    },

    add: function (key, object) {
      objects[key] = object;
    },

    remove: function (key) {
      delete objects[key];
    },

    removeAll: function () {
      objects = {};
    },
  };
}

/*********************************/
/********** EXTENSIONS ***********/
/*********************************/

const EXTENSIONS = {
  KHR_BINARY_GLTF: "KHR_binary_glTF",
  KHR_DRACO_MESH_COMPRESSION: "KHR_draco_mesh_compression",
  KHR_LIGHTS_PUNCTUAL: "KHR_lights_punctual",
  KHR_MATERIALS_CLEARCOAT: "KHR_materials_clearcoat",
  KHR_MATERIALS_IOR: "KHR_materials_ior",
  KHR_MATERIALS_SHEEN: "KHR_materials_sheen",
  KHR_MATERIALS_SPECULAR: "KHR_materials_specular",
  KHR_MATERIALS_TRANSMISSION: "KHR_materials_transmission",
  KHR_MATERIALS_IRIDESCENCE: "KHR_materials_iridescence",
  KHR_MATERIALS_UNLIT: "KHR_materials_unlit",
  KHR_MATERIALS_VOLUME: "KHR_materials_volume",
  KHR_TEXTURE_BASISU: "KHR_texture_basisu",
  KHR_TEXTURE_TRANSFORM: "KHR_texture_transform",
  KHR_MESH_QUANTIZATION: "KHR_mesh_quantization",
  KHR_MATERIALS_EMISSIVE_STRENGTH: "KHR_materials_emissive_strength",
  EXT_TEXTURE_WEBP: "EXT_texture_webp",
  EXT_MESHOPT_COMPRESSION: "EXT_meshopt_compression",
  EXT_MESH_GPU_INSTANCING: "EXT_mesh_gpu_instancing",
};

/**
 * Punctual Lights Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
 */
class GLTFLightsExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_LIGHTS_PUNCTUAL;

    // Object3D instance caches
    this.cache = { refs: {}, uses: {} };
  }

  _markDefs() {
    const parser = this.parser;
    const nodeDefs = this.parser.json.nodes || [];

    for (
      let nodeIndex = 0, nodeLength = nodeDefs.length;
      nodeIndex < nodeLength;
      nodeIndex++
    ) {
      const nodeDef = nodeDefs[nodeIndex];

      if (
        nodeDef.extensions &&
        nodeDef.extensions[this.name] &&
        nodeDef.extensions[this.name].light !== undefined
      ) {
        parser._addNodeRef(this.cache, nodeDef.extensions[this.name].light);
      }
    }
  }

  _loadLight(lightIndex) {
    const parser = this.parser;
    const cacheKey = "light:" + lightIndex;
    let dependency = parser.cache.get(cacheKey);

    if (dependency) return dependency;

    const json = parser.json;
    const extensions = (json.extensions && json.extensions[this.name]) || {};
    const lightDefs = extensions.lights || [];
    const lightDef = lightDefs[lightIndex];
    let lightNode;

    const color = new Color(0xffffff);

    if (lightDef.color !== undefined) color.fromArray(lightDef.color);

    const range = lightDef.range !== undefined ? lightDef.range : 0;

    switch (lightDef.type) {
      case "directional":
        lightNode = new DirectionalLight(color);
        lightNode.target.position.set(0, 0, -1);
        lightNode.add(lightNode.target);
        break;

      case "point":
        lightNode = new PointLight(color);
        lightNode.distance = range;
        break;

      case "spot":
        lightNode = new SpotLight(color);
        lightNode.distance = range;
        // Handle spotlight properties.
        lightDef.spot = lightDef.spot || {};
        lightDef.spot.innerConeAngle =
          lightDef.spot.innerConeAngle !== undefined
            ? lightDef.spot.innerConeAngle
            : 0;
        lightDef.spot.outerConeAngle =
          lightDef.spot.outerConeAngle !== undefined
            ? lightDef.spot.outerConeAngle
            : Math.PI / 4.0;
        lightNode.angle = lightDef.spot.outerConeAngle;
        lightNode.penumbra =
          1.0 - lightDef.spot.innerConeAngle / lightDef.spot.outerConeAngle;
        lightNode.target.position.set(0, 0, -1);
        lightNode.add(lightNode.target);
        break;

      default:
        throw new Error(
          "THREE.GLTFLoader: Unexpected light type: " + lightDef.type
        );
    }

    // Some lights (e.g. spot) default to a position other than the origin. Reset the position
    // here, because node-level parsing will only override position if explicitly specified.
    lightNode.position.set(0, 0, 0);

    lightNode.decay = 2;

    assignExtrasToUserData(lightNode, lightDef);

    if (lightDef.intensity !== undefined)
      lightNode.intensity = lightDef.intensity;

    lightNode.name = parser.createUniqueName(
      lightDef.name || "light_" + lightIndex
    );

    dependency = Promise.resolve(lightNode);

    parser.cache.add(cacheKey, dependency);

    return dependency;
  }

  getDependency(type, index) {
    if (type !== "light") return;

    return this._loadLight(index);
  }

  createNodeAttachment(nodeIndex) {
    const self = this;
    const parser = this.parser;
    const json = parser.json;
    const nodeDef = json.nodes[nodeIndex];
    const lightDef =
      (nodeDef.extensions && nodeDef.extensions[this.name]) || {};
    const lightIndex = lightDef.light;

    if (lightIndex === undefined) return null;

    return this._loadLight(lightIndex).then(function (light) {
      return parser._getNodeRef(self.cache, lightIndex, light);
    });
  }
}

/**
 * Unlit Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_unlit
 */
class GLTFMaterialsUnlitExtension {
  constructor() {
    this.name = EXTENSIONS.KHR_MATERIALS_UNLIT;
  }

  getMaterialType() {
    return MeshBasicMaterial;
  }

  extendParams(materialParams, materialDef, parser) {
    const pending = [];

    materialParams.color = new Color(1.0, 1.0, 1.0);
    materialParams.opacity = 1.0;

    const metallicRoughness = materialDef.pbrMetallicRoughness;

    if (metallicRoughness) {
      if (Array.isArray(metallicRoughness.baseColorFactor)) {
        const array = metallicRoughness.baseColorFactor;

        materialParams.color.fromArray(array);
        materialParams.opacity = array[3];
      }

      if (metallicRoughness.baseColorTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "map",
            metallicRoughness.baseColorTexture,
            sRGBEncoding
          )
        );
      }
    }

    return Promise.all(pending);
  }
}

/**
 * Materials Emissive Strength Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/blob/5768b3ce0ef32bc39cdf1bef10b948586635ead3/extensions/2.0/Khronos/KHR_materials_emissive_strength/README.md
 */
class GLTFMaterialsEmissiveStrengthExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_EMISSIVE_STRENGTH;
  }

  extendMaterialParams(materialIndex, materialParams) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {
      return Promise.resolve();
    }

    const emissiveStrength = materialDef.extensions[this.name].emissiveStrength;

    if (emissiveStrength !== undefined) {
      materialParams.emissiveIntensity = emissiveStrength;
    }

    return Promise.resolve();
  }
}

/**
 * Clearcoat Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_clearcoat
 */
class GLTFMaterialsClearcoatExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_CLEARCOAT;
  }

  getMaterialType(materialIndex) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name])
      return null;

    return MeshPhysicalMaterial;
  }

  extendMaterialParams(materialIndex, materialParams) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {
      return Promise.resolve();
    }

    const pending = [];

    const extension = materialDef.extensions[this.name];

    if (extension.clearcoatFactor !== undefined) {
      materialParams.clearcoat = extension.clearcoatFactor;
    }

    if (extension.clearcoatTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "clearcoatMap",
          extension.clearcoatTexture
        )
      );
    }

    if (extension.clearcoatRoughnessFactor !== undefined) {
      materialParams.clearcoatRoughness = extension.clearcoatRoughnessFactor;
    }

    if (extension.clearcoatRoughnessTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "clearcoatRoughnessMap",
          extension.clearcoatRoughnessTexture
        )
      );
    }

    if (extension.clearcoatNormalTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "clearcoatNormalMap",
          extension.clearcoatNormalTexture
        )
      );

      if (extension.clearcoatNormalTexture.scale !== undefined) {
        const scale = extension.clearcoatNormalTexture.scale;

        materialParams.clearcoatNormalScale = new Vector2(scale, scale);
      }
    }

    return Promise.all(pending);
  }
}

/**
 * Iridescence Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_iridescence
 */
class GLTFMaterialsIridescenceExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_IRIDESCENCE;
  }

  getMaterialType(materialIndex) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name])
      return null;

    return MeshPhysicalMaterial;
  }

  extendMaterialParams(materialIndex, materialParams) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {
      return Promise.resolve();
    }

    const pending = [];

    const extension = materialDef.extensions[this.name];

    if (extension.iridescenceFactor !== undefined) {
      materialParams.iridescence = extension.iridescenceFactor;
    }

    if (extension.iridescenceTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "iridescenceMap",
          extension.iridescenceTexture
        )
      );
    }

    if (extension.iridescenceIor !== undefined) {
      materialParams.iridescenceIOR = extension.iridescenceIor;
    }

    if (materialParams.iridescenceThicknessRange === undefined) {
      materialParams.iridescenceThicknessRange = [100, 400];
    }

    if (extension.iridescenceThicknessMinimum !== undefined) {
      materialParams.iridescenceThicknessRange[0] =
        extension.iridescenceThicknessMinimum;
    }

    if (extension.iridescenceThicknessMaximum !== undefined) {
      materialParams.iridescenceThicknessRange[1] =
        extension.iridescenceThicknessMaximum;
    }

    if (extension.iridescenceThicknessTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "iridescenceThicknessMap",
          extension.iridescenceThicknessTexture
        )
      );
    }

    return Promise.all(pending);
  }
}

/**
 * Sheen Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/main/extensions/2.0/Khronos/KHR_materials_sheen
 */
class GLTFMaterialsSheenExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_SHEEN;
  }

  getMaterialType(materialIndex) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name])
      return null;

    return MeshPhysicalMaterial;
  }

  extendMaterialParams(materialIndex, materialParams) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {
      return Promise.resolve();
    }

    const pending = [];

    materialParams.sheenColor = new Color(0, 0, 0);
    materialParams.sheenRoughness = 0;
    materialParams.sheen = 1;

    const extension = materialDef.extensions[this.name];

    if (extension.sheenColorFactor !== undefined) {
      materialParams.sheenColor.fromArray(extension.sheenColorFactor);
    }

    if (extension.sheenRoughnessFactor !== undefined) {
      materialParams.sheenRoughness = extension.sheenRoughnessFactor;
    }

    if (extension.sheenColorTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "sheenColorMap",
          extension.sheenColorTexture,
          sRGBEncoding
        )
      );
    }

    if (extension.sheenRoughnessTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "sheenRoughnessMap",
          extension.sheenRoughnessTexture
        )
      );
    }

    return Promise.all(pending);
  }
}

/**
 * Transmission Materials Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_transmission
 * Draft: https://github.com/KhronosGroup/glTF/pull/1698
 */
class GLTFMaterialsTransmissionExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_TRANSMISSION;
  }

  getMaterialType(materialIndex) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name])
      return null;

    return MeshPhysicalMaterial;
  }

  extendMaterialParams(materialIndex, materialParams) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {
      return Promise.resolve();
    }

    const pending = [];

    const extension = materialDef.extensions[this.name];

    if (extension.transmissionFactor !== undefined) {
      materialParams.transmission = extension.transmissionFactor;
    }

    if (extension.transmissionTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "transmissionMap",
          extension.transmissionTexture
        )
      );
    }

    return Promise.all(pending);
  }
}

/**
 * Materials Volume Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_volume
 */
class GLTFMaterialsVolumeExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_VOLUME;
  }

  getMaterialType(materialIndex) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name])
      return null;

    return MeshPhysicalMaterial;
  }

  extendMaterialParams(materialIndex, materialParams) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {
      return Promise.resolve();
    }

    const pending = [];

    const extension = materialDef.extensions[this.name];

    materialParams.thickness =
      extension.thicknessFactor !== undefined ? extension.thicknessFactor : 0;

    if (extension.thicknessTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "thicknessMap",
          extension.thicknessTexture
        )
      );
    }

    materialParams.attenuationDistance =
      extension.attenuationDistance || Infinity;

    const colorArray = extension.attenuationColor || [1, 1, 1];
    materialParams.attenuationColor = new Color(
      colorArray[0],
      colorArray[1],
      colorArray[2]
    );

    return Promise.all(pending);
  }
}

/**
 * Materials ior Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_ior
 */
class GLTFMaterialsIorExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_IOR;
  }

  getMaterialType(materialIndex) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name])
      return null;

    return MeshPhysicalMaterial;
  }

  extendMaterialParams(materialIndex, materialParams) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {
      return Promise.resolve();
    }

    const extension = materialDef.extensions[this.name];

    materialParams.ior = extension.ior !== undefined ? extension.ior : 1.5;

    return Promise.resolve();
  }
}

/**
 * Materials specular Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_materials_specular
 */
class GLTFMaterialsSpecularExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_SPECULAR;
  }

  getMaterialType(materialIndex) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name])
      return null;

    return MeshPhysicalMaterial;
  }

  extendMaterialParams(materialIndex, materialParams) {
    const parser = this.parser;
    const materialDef = parser.json.materials[materialIndex];

    if (!materialDef.extensions || !materialDef.extensions[this.name]) {
      return Promise.resolve();
    }

    const pending = [];

    const extension = materialDef.extensions[this.name];

    materialParams.specularIntensity =
      extension.specularFactor !== undefined ? extension.specularFactor : 1.0;

    if (extension.specularTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "specularIntensityMap",
          extension.specularTexture
        )
      );
    }

    const colorArray = extension.specularColorFactor || [1, 1, 1];
    materialParams.specularColor = new Color(
      colorArray[0],
      colorArray[1],
      colorArray[2]
    );

    if (extension.specularColorTexture !== undefined) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "specularColorMap",
          extension.specularColorTexture,
          sRGBEncoding
        )
      );
    }

    return Promise.all(pending);
  }
}

/**
 * BasisU Texture Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_basisu
 */
class GLTFTextureBasisUExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_TEXTURE_BASISU;
  }

  loadTexture(textureIndex) {
    const parser = this.parser;
    const json = parser.json;

    const textureDef = json.textures[textureIndex];

    if (!textureDef.extensions || !textureDef.extensions[this.name]) {
      return null;
    }

    const extension = textureDef.extensions[this.name];
    const loader = parser.options.ktx2Loader;

    if (!loader) {
      if (
        json.extensionsRequired &&
        json.extensionsRequired.indexOf(this.name) >= 0
      ) {
        throw new Error(
          "THREE.GLTFLoader: setKTX2Loader must be called before loading KTX2 textures"
        );
      } else {
        // Assumes that the extension is optional and that a fallback texture is present
        return null;
      }
    }

    return parser.loadTextureImage(textureIndex, extension.source, loader);
  }
}

/**
 * WebP Texture Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_texture_webp
 */
class GLTFTextureWebPExtension {
  constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.EXT_TEXTURE_WEBP;
    this.isSupported = null;
  }

  loadTexture(textureIndex) {
    const name = this.name;
    const parser = this.parser;
    const json = parser.json;

    const textureDef = json.textures[textureIndex];

    if (!textureDef.extensions || !textureDef.extensions[name]) {
      return null;
    }

    const extension = textureDef.extensions[name];
    const source = json.images[extension.source];

    let loader = parser.textureLoader;
    if (source.uri) {
      const handler = parser.options.manager.getHandler(source.uri);
      if (handler !== null) loader = handler;
    }

    return this.detectSupport().then(function (isSupported) {
      if (isSupported)
        return parser.loadTextureImage(textureIndex, extension.source, loader);

      if (
        json.extensionsRequired &&
        json.extensionsRequired.indexOf(name) >= 0
      ) {
        throw new Error(
          "THREE.GLTFLoader: WebP required by asset but unsupported."
        );
      }

      // Fall back to PNG or JPEG.
      return parser.loadTexture(textureIndex);
    });
  }

  detectSupport() {
    if (!this.isSupported) {
      this.isSupported = new Promise(function (resolve) {
        const image = new Image();

        // Lossy test image. Support for lossy images doesn't guarantee support for all
        // WebP images, unfortunately.
        image.src =
          "";

        image.onload = image.onerror = function () {
          resolve(image.height === 1);
        };
      });
    }

    return this.isSupported;
  }
}

/**
 * meshopt BufferView Compression Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_meshopt_compression
 */
class GLTFMeshoptCompression {
  constructor(parser) {
    this.name = EXTENSIONS.EXT_MESHOPT_COMPRESSION;
    this.parser = parser;
  }

  loadBufferView(index) {
    const json = this.parser.json;
    const bufferView = json.bufferViews[index];

    if (bufferView.extensions && bufferView.extensions[this.name]) {
      const extensionDef = bufferView.extensions[this.name];

      const buffer = this.parser.getDependency("buffer", extensionDef.buffer);
      const decoder = this.parser.options.meshoptDecoder;

      if (!decoder || !decoder.supported) {
        if (
          json.extensionsRequired &&
          json.extensionsRequired.indexOf(this.name) >= 0
        ) {
          throw new Error(
            "THREE.GLTFLoader: setMeshoptDecoder must be called before loading compressed files"
          );
        } else {
          // Assumes that the extension is optional and that fallback buffer data is present
          return null;
        }
      }

      return buffer.then(function (res) {
        const byteOffset = extensionDef.byteOffset || 0;
        const byteLength = extensionDef.byteLength || 0;

        const count = extensionDef.count;
        const stride = extensionDef.byteStride;

        const source = new Uint8Array(res, byteOffset, byteLength);

        if (decoder.decodeGltfBufferAsync) {
          return decoder
            .decodeGltfBufferAsync(
              count,
              stride,
              source,
              extensionDef.mode,
              extensionDef.filter
            )
            .then(function (res) {
              return res.buffer;
            });
        } else {
          // Support for MeshoptDecoder 0.18 or earlier, without decodeGltfBufferAsync
          return decoder.ready.then(function () {
            const result = new ArrayBuffer(count * stride);
            decoder.decodeGltfBuffer(
              new Uint8Array(result),
              count,
              stride,
              source,
              extensionDef.mode,
              extensionDef.filter
            );
            return result;
          });
        }
      });
    } else {
      return null;
    }
  }
}

/**
 * GPU Instancing Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Vendor/EXT_mesh_gpu_instancing
 *
 */
class GLTFMeshGpuInstancing {
  constructor(parser) {
    this.name = EXTENSIONS.EXT_MESH_GPU_INSTANCING;
    this.parser = parser;
  }

  createNodeMesh(nodeIndex) {
    const json = this.parser.json;
    const nodeDef = json.nodes[nodeIndex];

    if (
      !nodeDef.extensions ||
      !nodeDef.extensions[this.name] ||
      nodeDef.mesh === undefined
    ) {
      return null;
    }

    const meshDef = json.meshes[nodeDef.mesh];

    // No Points or Lines + Instancing support yet

    for (const primitive of meshDef.primitives) {
      if (
        primitive.mode !== WEBGL_CONSTANTS.TRIANGLES &&
        primitive.mode !== WEBGL_CONSTANTS.TRIANGLE_STRIP &&
        primitive.mode !== WEBGL_CONSTANTS.TRIANGLE_FAN &&
        primitive.mode !== undefined
      ) {
        return null;
      }
    }

    const extensionDef = nodeDef.extensions[this.name];
    const attributesDef = extensionDef.attributes;

    // @TODO: Can we support InstancedMesh + SkinnedMesh?

    const pending = [];
    const attributes = {};

    for (const key in attributesDef) {
      pending.push(
        this.parser
          .getDependency("accessor", attributesDef[key])
          .then((accessor) => {
            attributes[key] = accessor;
            return attributes[key];
          })
      );
    }

    if (pending.length < 1) {
      return null;
    }

    pending.push(this.parser.createNodeMesh(nodeIndex));

    return Promise.all(pending).then((results) => {
      const nodeObject = results.pop();
      const meshes = nodeObject.isGroup ? nodeObject.children : [nodeObject];
      const count = results[0].count; // All attribute counts should be same
      const instancedMeshes = [];

      for (const mesh of meshes) {
        // Temporal variables
        const m = new Matrix4();
        const p = new Vector3();
        const q = new Quaternion();
        const s = new Vector3(1, 1, 1);

        const instancedMesh = new InstancedMesh(
          mesh.geometry,
          mesh.material,
          count
        );

        for (let i = 0; i < count; i++) {
          if (attributes.TRANSLATION) {
            p.fromBufferAttribute(attributes.TRANSLATION, i);
          }

          if (attributes.ROTATION) {
            q.fromBufferAttribute(attributes.ROTATION, i);
          }

          if (attributes.SCALE) {
            s.fromBufferAttribute(attributes.SCALE, i);
          }

          instancedMesh.setMatrixAt(i, m.compose(p, q, s));
        }

        // Add instance attributes to the geometry, excluding TRS.
        for (const attributeName in attributes) {
          if (
            attributeName !== "TRANSLATION" &&
            attributeName !== "ROTATION" &&
            attributeName !== "SCALE"
          ) {
            mesh.geometry.setAttribute(
              attributeName,
              attributes[attributeName]
            );
          }
        }

        // Just in case
        Object3D.prototype.copy.call(instancedMesh, mesh);

        // https://github.com/mrdoob/three.js/issues/18334
        instancedMesh.frustumCulled = false;
        this.parser.assignFinalMaterial(instancedMesh);

        instancedMeshes.push(instancedMesh);
      }

      if (nodeObject.isGroup) {
        nodeObject.clear();

        nodeObject.add(...instancedMeshes);

        return nodeObject;
      }

      return instancedMeshes[0];
    });
  }
}

/* BINARY EXTENSION */
const BINARY_EXTENSION_HEADER_MAGIC = "glTF";
const BINARY_EXTENSION_HEADER_LENGTH = 12;
const BINARY_EXTENSION_CHUNK_TYPES = { JSON: 0x4e4f534a, BIN: 0x004e4942 };

class GLTFBinaryExtension {
  constructor(data) {
    this.name = EXTENSIONS.KHR_BINARY_GLTF;
    this.content = null;
    this.body = null;

    const headerView = new DataView(data, 0, BINARY_EXTENSION_HEADER_LENGTH);

    this.header = {
      magic: LoaderUtils.decodeText(new Uint8Array(data.slice(0, 4))),
      version: headerView.getUint32(4, true),
      length: headerView.getUint32(8, true),
    };

    if (this.header.magic !== BINARY_EXTENSION_HEADER_MAGIC) {
      throw new Error("THREE.GLTFLoader: Unsupported glTF-Binary header.");
    } else if (this.header.version < 2.0) {
      throw new Error("THREE.GLTFLoader: Legacy binary file detected.");
    }

    const chunkContentsLength =
      this.header.length - BINARY_EXTENSION_HEADER_LENGTH;
    const chunkView = new DataView(data, BINARY_EXTENSION_HEADER_LENGTH);
    let chunkIndex = 0;

    while (chunkIndex < chunkContentsLength) {
      const chunkLength = chunkView.getUint32(chunkIndex, true);
      chunkIndex += 4;

      const chunkType = chunkView.getUint32(chunkIndex, true);
      chunkIndex += 4;

      if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.JSON) {
        const contentArray = new Uint8Array(
          data,
          BINARY_EXTENSION_HEADER_LENGTH + chunkIndex,
          chunkLength
        );
        this.content = LoaderUtils.decodeText(contentArray);
      } else if (chunkType === BINARY_EXTENSION_CHUNK_TYPES.BIN) {
        const byteOffset = BINARY_EXTENSION_HEADER_LENGTH + chunkIndex;
        this.body = data.slice(byteOffset, byteOffset + chunkLength);
      }

      // Clients must ignore chunks with unknown types.

      chunkIndex += chunkLength;
    }

    if (this.content === null) {
      throw new Error("THREE.GLTFLoader: JSON content not found.");
    }
  }
}

/**
 * DRACO Mesh Compression Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_draco_mesh_compression
 */
class GLTFDracoMeshCompressionExtension {
  constructor(json, dracoLoader) {
    if (!dracoLoader) {
      throw new Error("THREE.GLTFLoader: No DRACOLoader instance provided.");
    }

    this.name = EXTENSIONS.KHR_DRACO_MESH_COMPRESSION;
    this.json = json;
    this.dracoLoader = dracoLoader;
    this.dracoLoader.preload();
  }

  decodePrimitive(primitive, parser) {
    const json = this.json;
    const dracoLoader = this.dracoLoader;
    const bufferViewIndex = primitive.extensions[this.name].bufferView;
    const gltfAttributeMap = primitive.extensions[this.name].attributes;
    const threeAttributeMap = {};
    const attributeNormalizedMap = {};
    const attributeTypeMap = {};

    for (const attributeName in gltfAttributeMap) {
      const threeAttributeName =
        ATTRIBUTES[attributeName] || attributeName.toLowerCase();

      threeAttributeMap[threeAttributeName] = gltfAttributeMap[attributeName];
    }

    for (const attributeName in primitive.attributes) {
      const threeAttributeName =
        ATTRIBUTES[attributeName] || attributeName.toLowerCase();

      if (gltfAttributeMap[attributeName] !== undefined) {
        const accessorDef = json.accessors[primitive.attributes[attributeName]];
        const componentType = WEBGL_COMPONENT_TYPES[accessorDef.componentType];

        attributeTypeMap[threeAttributeName] = componentType.name;
        attributeNormalizedMap[threeAttributeName] =
          accessorDef.normalized === true;
      }
    }

    return parser
      .getDependency("bufferView", bufferViewIndex)
      .then(function (bufferView) {
        return new Promise(function (resolve) {
          dracoLoader.decodeDracoFile(
            bufferView,
            function (geometry) {
              for (const attributeName in geometry.attributes) {
                const attribute = geometry.attributes[attributeName];
                const normalized = attributeNormalizedMap[attributeName];

                if (normalized !== undefined) attribute.normalized = normalized;
              }

              resolve(geometry);
            },
            threeAttributeMap,
            attributeTypeMap
          );
        });
      });
  }
}

/**
 * Texture Transform Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_texture_transform
 */
class GLTFTextureTransformExtension {
  constructor() {
    this.name = EXTENSIONS.KHR_TEXTURE_TRANSFORM;
  }

  extendTexture(texture, transform) {
    if (transform.texCoord !== undefined) {
      console.warn(
        'THREE.GLTFLoader: Custom UV sets in "' +
          this.name +
          '" extension not yet supported.'
      );
    }

    if (
      transform.offset === undefined &&
      transform.rotation === undefined &&
      transform.scale === undefined
    ) {
      // See https://github.com/mrdoob/three.js/issues/21819.
      return texture;
    }

    texture = texture.clone();

    if (transform.offset !== undefined) {
      texture.offset.fromArray(transform.offset);
    }

    if (transform.rotation !== undefined) {
      texture.rotation = transform.rotation;
    }

    if (transform.scale !== undefined) {
      texture.repeat.fromArray(transform.scale);
    }

    texture.needsUpdate = true;

    return texture;
  }
}

/**
 * Mesh Quantization Extension
 *
 * Specification: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization
 */
class GLTFMeshQuantizationExtension {
  constructor() {
    this.name = EXTENSIONS.KHR_MESH_QUANTIZATION;
  }
}

/*********************************/
/********** INTERPOLATION ********/
/*********************************/

// Spline Interpolation
// Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#appendix-c-spline-interpolation
class GLTFCubicSplineInterpolant extends Interpolant {
  constructor(parameterPositions, sampleValues, sampleSize, resultBuffer) {
    super(parameterPositions, sampleValues, sampleSize, resultBuffer);
  }

  copySampleValue_(index) {
    // Copies a sample value to the result buffer. See description of glTF
    // CUBICSPLINE values layout in interpolate_() function below.

    const result = this.resultBuffer,
      values = this.sampleValues,
      valueSize = this.valueSize,
      offset = index * valueSize * 3 + valueSize;

    for (let i = 0; i !== valueSize; i++) {
      result[i] = values[offset + i];
    }

    return result;
  }

  interpolate_(i1, t0, t, t1) {
    const result = this.resultBuffer;
    const values = this.sampleValues;
    const stride = this.valueSize;

    const stride2 = stride * 2;
    const stride3 = stride * 3;

    const td = t1 - t0;

    const p = (t - t0) / td;
    const pp = p * p;
    const ppp = pp * p;

    const offset1 = i1 * stride3;
    const offset0 = offset1 - stride3;

    const s2 = -2 * ppp + 3 * pp;
    const s3 = ppp - pp;
    const s0 = 1 - s2;
    const s1 = s3 - pp + p;

    // Layout of keyframe output values for CUBICSPLINE animations:
    //   [ inTangent_1, splineVertex_1, outTangent_1, inTangent_2, splineVertex_2, ... ]
    for (let i = 0; i !== stride; i++) {
      const p0 = values[offset0 + i + stride]; // splineVertex_k
      const m0 = values[offset0 + i + stride2] * td; // outTangent_k * (t_k+1 - t_k)
      const p1 = values[offset1 + i + stride]; // splineVertex_k+1
      const m1 = values[offset1 + i] * td; // inTangent_k+1 * (t_k+1 - t_k)

      result[i] = s0 * p0 + s1 * m0 + s2 * p1 + s3 * m1;
    }

    return result;
  }
}

const _q = new Quaternion();

class GLTFCubicSplineQuaternionInterpolant extends GLTFCubicSplineInterpolant {
  interpolate_(i1, t0, t, t1) {
    const result = super.interpolate_(i1, t0, t, t1);

    _q.fromArray(result).normalize().toArray(result);

    return result;
  }
}

/*********************************/
/********** INTERNALS ************/
/*********************************/

/* CONSTANTS */

const WEBGL_CONSTANTS = {
  FLOAT: 5126,
  //FLOAT_MAT2: 35674,
  FLOAT_MAT3: 35675,
  FLOAT_MAT4: 35676,
  FLOAT_VEC2: 35664,
  FLOAT_VEC3: 35665,
  FLOAT_VEC4: 35666,
  LINEAR: 9729,
  REPEAT: 10497,
  SAMPLER_2D: 35678,
  POINTS: 0,
  LINES: 1,
  LINE_LOOP: 2,
  LINE_STRIP: 3,
  TRIANGLES: 4,
  TRIANGLE_STRIP: 5,
  TRIANGLE_FAN: 6,
  UNSIGNED_BYTE: 5121,
  UNSIGNED_SHORT: 5123,
};

const WEBGL_COMPONENT_TYPES = {
  5120: Int8Array,
  5121: Uint8Array,
  5122: Int16Array,
  5123: Uint16Array,
  5125: Uint32Array,
  5126: Float32Array,
};

const WEBGL_FILTERS = {
  9728: NearestFilter,
  9729: LinearFilter,
  9984: NearestMipmapNearestFilter,
  9985: LinearMipmapNearestFilter,
  9986: NearestMipmapLinearFilter,
  9987: LinearMipmapLinearFilter,
};

const WEBGL_WRAPPINGS = {
  33071: ClampToEdgeWrapping,
  33648: MirroredRepeatWrapping,
  10497: RepeatWrapping,
};

const WEBGL_TYPE_SIZES = {
  SCALAR: 1,
  VEC2: 2,
  VEC3: 3,
  VEC4: 4,
  MAT2: 4,
  MAT3: 9,
  MAT4: 16,
};

const ATTRIBUTES = {
  POSITION: "position",
  NORMAL: "normal",
  TANGENT: "tangent",
  TEXCOORD_0: "uv",
  TEXCOORD_1: "uv2",
  COLOR_0: "color",
  WEIGHTS_0: "skinWeight",
  JOINTS_0: "skinIndex",
};

const PATH_PROPERTIES = {
  scale: "scale",
  translation: "position",
  rotation: "quaternion",
  weights: "morphTargetInfluences",
};

const INTERPOLATION = {
  CUBICSPLINE: undefined, // We use a custom interpolant (GLTFCubicSplineInterpolation) for CUBICSPLINE tracks. Each
  // keyframe track will be initialized with a default interpolation type, then modified.
  LINEAR: InterpolateLinear,
  STEP: InterpolateDiscrete,
};

const ALPHA_MODES = {
  OPAQUE: "OPAQUE",
  MASK: "MASK",
  BLEND: "BLEND",
};

/**
 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#default-material
 */
function createDefaultMaterial(cache) {
  if (cache["DefaultMaterial"] === undefined) {
    cache["DefaultMaterial"] = new MeshStandardMaterial({
      color: 0xffffff,
      emissive: 0x000000,
      metalness: 1,
      roughness: 1,
      transparent: false,
      depthTest: true,
      side: FrontSide,
    });
  }

  return cache["DefaultMaterial"];
}

function addUnknownExtensionsToUserData(knownExtensions, object, objectDef) {
  // Add unknown glTF extensions to an object's userData.

  for (const name in objectDef.extensions) {
    if (knownExtensions[name] === undefined) {
      object.userData.gltfExtensions = object.userData.gltfExtensions || {};
      object.userData.gltfExtensions[name] = objectDef.extensions[name];
    }
  }
}

/**
 * @param {Object3D|Material|BufferGeometry} object
 * @param {GLTF.definition} gltfDef
 */
function assignExtrasToUserData(object, gltfDef) {
  if (gltfDef.extras !== undefined) {
    if (typeof gltfDef.extras === "object") {
      Object.assign(object.userData, gltfDef.extras);
    } else {
      console.warn(
        "THREE.GLTFLoader: Ignoring primitive type .extras, " + gltfDef.extras
      );
    }
  }
}

/**
 * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#morph-targets
 *
 * @param {BufferGeometry} geometry
 * @param {Array<GLTF.Target>} targets
 * @param {GLTFParser} parser
 * @return {Promise<BufferGeometry>}
 */
function addMorphTargets(geometry, targets, parser) {
  let hasMorphPosition = false;
  let hasMorphNormal = false;
  let hasMorphColor = false;

  for (let i = 0, il = targets.length; i < il; i++) {
    const target = targets[i];

    if (target.POSITION !== undefined) hasMorphPosition = true;
    if (target.NORMAL !== undefined) hasMorphNormal = true;
    if (target.COLOR_0 !== undefined) hasMorphColor = true;

    if (hasMorphPosition && hasMorphNormal && hasMorphColor) break;
  }

  if (!hasMorphPosition && !hasMorphNormal && !hasMorphColor)
    return Promise.resolve(geometry);

  const pendingPositionAccessors = [];
  const pendingNormalAccessors = [];
  const pendingColorAccessors = [];

  for (let i = 0, il = targets.length; i < il; i++) {
    const target = targets[i];

    if (hasMorphPosition) {
      const pendingAccessor =
        target.POSITION !== undefined
          ? parser.getDependency("accessor", target.POSITION)
          : geometry.attributes.position;

      pendingPositionAccessors.push(pendingAccessor);
    }

    if (hasMorphNormal) {
      const pendingAccessor =
        target.NORMAL !== undefined
          ? parser.getDependency("accessor", target.NORMAL)
          : geometry.attributes.normal;

      pendingNormalAccessors.push(pendingAccessor);
    }

    if (hasMorphColor) {
      const pendingAccessor =
        target.COLOR_0 !== undefined
          ? parser.getDependency("accessor", target.COLOR_0)
          : geometry.attributes.color;

      pendingColorAccessors.push(pendingAccessor);
    }
  }

  return Promise.all([
    Promise.all(pendingPositionAccessors),
    Promise.all(pendingNormalAccessors),
    Promise.all(pendingColorAccessors),
  ]).then(function (accessors) {
    const morphPositions = accessors[0];
    const morphNormals = accessors[1];
    const morphColors = accessors[2];

    if (hasMorphPosition) geometry.morphAttributes.position = morphPositions;
    if (hasMorphNormal) geometry.morphAttributes.normal = morphNormals;
    if (hasMorphColor) geometry.morphAttributes.color = morphColors;
    geometry.morphTargetsRelative = true;

    return geometry;
  });
}

/**
 * @param {Mesh} mesh
 * @param {GLTF.Mesh} meshDef
 */
function updateMorphTargets(mesh, meshDef) {
  mesh.updateMorphTargets();

  if (meshDef.weights !== undefined) {
    for (let i = 0, il = meshDef.weights.length; i < il; i++) {
      mesh.morphTargetInfluences[i] = meshDef.weights[i];
    }
  }

  // .extras has user-defined data, so check that .extras.targetNames is an array.
  if (meshDef.extras && Array.isArray(meshDef.extras.targetNames)) {
    const targetNames = meshDef.extras.targetNames;

    if (mesh.morphTargetInfluences.length === targetNames.length) {
      mesh.morphTargetDictionary = {};

      for (let i = 0, il = targetNames.length; i < il; i++) {
        mesh.morphTargetDictionary[targetNames[i]] = i;
      }
    } else {
      console.warn(
        "THREE.GLTFLoader: Invalid extras.targetNames length. Ignoring names."
      );
    }
  }
}

function createPrimitiveKey(primitiveDef) {
  const dracoExtension =
    primitiveDef.extensions &&
    primitiveDef.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION];
  let geometryKey;

  if (dracoExtension) {
    geometryKey =
      "draco:" +
      dracoExtension.bufferView +
      ":" +
      dracoExtension.indices +
      ":" +
      createAttributesKey(dracoExtension.attributes);
  } else {
    geometryKey =
      primitiveDef.indices +
      ":" +
      createAttributesKey(primitiveDef.attributes) +
      ":" +
      primitiveDef.mode;
  }

  return geometryKey;
}

function createAttributesKey(attributes) {
  let attributesKey = "";

  const keys = Object.keys(attributes).sort();

  for (let i = 0, il = keys.length; i < il; i++) {
    attributesKey += keys[i] + ":" + attributes[keys[i]] + ";";
  }

  return attributesKey;
}

function getNormalizedComponentScale(constructor) {
  // Reference:
  // https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_mesh_quantization#encoding-quantized-data

  switch (constructor) {
    case Int8Array:
      return 1 / 127;

    case Uint8Array:
      return 1 / 255;

    case Int16Array:
      return 1 / 32767;

    case Uint16Array:
      return 1 / 65535;

    default:
      throw new Error(
        "THREE.GLTFLoader: Unsupported normalized accessor component type."
      );
  }
}

function getImageURIMimeType(uri) {
  if (
    uri.search(/\.jpe?g($|\?)/i) > 0 ||
    uri.search(/^data\:image\/jpeg/) === 0
  )
    return "image/jpeg";
  if (uri.search(/\.webp($|\?)/i) > 0 || uri.search(/^data\:image\/webp/) === 0)
    return "image/webp";

  return "image/png";
}

/* GLTF PARSER */

class GLTFParser {
  constructor(json = {}, options = {}) {
    this.json = json;
    this.extensions = {};
    this.plugins = {};
    this.options = options;

    // loader object cache
    this.cache = new GLTFRegistry();

    // associations between Three.js objects and glTF elements
    this.associations = new Map();

    // BufferGeometry caching
    this.primitiveCache = {};

    // Object3D instance caches
    this.meshCache = { refs: {}, uses: {} };
    this.cameraCache = { refs: {}, uses: {} };
    this.lightCache = { refs: {}, uses: {} };

    this.sourceCache = {};
    this.textureCache = {};

    // Track node names, to ensure no duplicates
    this.nodeNamesUsed = {};

    // Use an ImageBitmapLoader if imageBitmaps are supported. Moves much of the
    // expensive work of uploading a texture to the GPU off the main thread.

    let isSafari = false;
    let isFirefox = false;
    let firefoxVersion = -1;

    if (typeof navigator !== "undefined") {
      isSafari =
        /^((?!chrome|android).)*safari/i.test(navigator.userAgent) === true;
      isFirefox = navigator.userAgent.indexOf("Firefox") > -1;
      firefoxVersion = isFirefox
        ? navigator.userAgent.match(/Firefox\/([0-9]+)\./)[1]
        : -1;
    }

    if (
      typeof createImageBitmap === "undefined" ||
      isSafari ||
      (isFirefox && firefoxVersion < 98)
    ) {
      this.textureLoader = new TextureLoader(this.options.manager);
    } else {
      this.textureLoader = new ImageBitmapLoader(this.options.manager);
    }

    this.textureLoader.setCrossOrigin(this.options.crossOrigin);
    this.textureLoader.setRequestHeader(this.options.requestHeader);

    this.fileLoader = new FileLoader(this.options.manager);
    this.fileLoader.setResponseType("arraybuffer");

    if (this.options.crossOrigin === "use-credentials") {
      this.fileLoader.setWithCredentials(true);
    }
  }

  setExtensions(extensions) {
    this.extensions = extensions;
  }

  setPlugins(plugins) {
    this.plugins = plugins;
  }

  parse(onLoad, onError) {
    const parser = this;
    const json = this.json;
    const extensions = this.extensions;

    // Clear the loader cache
    this.cache.removeAll();

    // Mark the special nodes/meshes in json for efficient parse
    this._invokeAll(function (ext) {
      return ext._markDefs && ext._markDefs();
    });

    Promise.all(
      this._invokeAll(function (ext) {
        return ext.beforeRoot && ext.beforeRoot();
      })
    )
      .then(function () {
        return Promise.all([
          parser.getDependencies("scene"),
          parser.getDependencies("animation"),
          parser.getDependencies("camera"),
        ]);
      })
      .then(function (dependencies) {
        const result = {
          scene: dependencies[0][json.scene || 0],
          scenes: dependencies[0],
          animations: dependencies[1],
          cameras: dependencies[2],
          asset: json.asset,
          parser: parser,
          userData: {},
        };

        addUnknownExtensionsToUserData(extensions, result, json);

        assignExtrasToUserData(result, json);

        Promise.all(
          parser._invokeAll(function (ext) {
            return ext.afterRoot && ext.afterRoot(result);
          })
        ).then(function () {
          onLoad(result);
        });
      })
      .catch(onError);
  }

  /**
   * Marks the special nodes/meshes in json for efficient parse.
   */
  _markDefs() {
    const nodeDefs = this.json.nodes || [];
    const skinDefs = this.json.skins || [];
    const meshDefs = this.json.meshes || [];

    // Nothing in the node definition indicates whether it is a Bone or an
    // Object3D. Use the skins' joint references to mark bones.
    for (
      let skinIndex = 0, skinLength = skinDefs.length;
      skinIndex < skinLength;
      skinIndex++
    ) {
      const joints = skinDefs[skinIndex].joints;

      for (let i = 0, il = joints.length; i < il; i++) {
        nodeDefs[joints[i]].isBone = true;
      }
    }

    // Iterate over all nodes, marking references to shared resources,
    // as well as skeleton joints.
    for (
      let nodeIndex = 0, nodeLength = nodeDefs.length;
      nodeIndex < nodeLength;
      nodeIndex++
    ) {
      const nodeDef = nodeDefs[nodeIndex];

      if (nodeDef.mesh !== undefined) {
        this._addNodeRef(this.meshCache, nodeDef.mesh);

        // Nothing in the mesh definition indicates whether it is
        // a SkinnedMesh or Mesh. Use the node's mesh reference
        // to mark SkinnedMesh if node has skin.
        if (nodeDef.skin !== undefined) {
          meshDefs[nodeDef.mesh].isSkinnedMesh = true;
        }
      }

      if (nodeDef.camera !== undefined) {
        this._addNodeRef(this.cameraCache, nodeDef.camera);
      }
    }
  }

  /**
   * Counts references to shared node / Object3D resources. These resources
   * can be reused, or "instantiated", at multiple nodes in the scene
   * hierarchy. Mesh, Camera, and Light instances are instantiated and must
   * be marked. Non-scenegraph resources (like Materials, Geometries, and
   * Textures) can be reused directly and are not marked here.
   *
   * Example: CesiumMilkTruck sample model reuses "Wheel" meshes.
   */
  _addNodeRef(cache, index) {
    if (index === undefined) return;

    if (cache.refs[index] === undefined) {
      cache.refs[index] = cache.uses[index] = 0;
    }

    cache.refs[index]++;
  }

  /** Returns a reference to a shared resource, cloning it if necessary. */
  _getNodeRef(cache, index, object) {
    if (cache.refs[index] <= 1) return object;

    const ref = object.clone();

    // Propagates mappings to the cloned object, prevents mappings on the
    // original object from being lost.
    const updateMappings = (original, clone) => {
      const mappings = this.associations.get(original);
      if (mappings != null) {
        this.associations.set(clone, mappings);
      }

      for (const [i, child] of original.children.entries()) {
        updateMappings(child, clone.children[i]);
      }
    };

    updateMappings(object, ref);

    ref.name += "_instance_" + cache.uses[index]++;

    return ref;
  }

  _invokeOne(func) {
    const extensions = Object.values(this.plugins);
    extensions.push(this);

    for (let i = 0; i < extensions.length; i++) {
      const result = func(extensions[i]);

      if (result) return result;
    }

    return null;
  }

  _invokeAll(func) {
    const extensions = Object.values(this.plugins);
    extensions.unshift(this);

    const pending = [];

    for (let i = 0; i < extensions.length; i++) {
      const result = func(extensions[i]);

      if (result) pending.push(result);
    }

    return pending;
  }

  /**
   * Requests the specified dependency asynchronously, with caching.
   * @param {string} type
   * @param {number} index
   * @return {Promise<Object3D|Material|THREE.Texture|AnimationClip|ArrayBuffer|Object>}
   */
  getDependency(type, index) {
    const cacheKey = type + ":" + index;
    let dependency = this.cache.get(cacheKey);

    if (!dependency) {
      switch (type) {
        case "scene":
          dependency = this.loadScene(index);
          break;

        case "node":
          dependency = this.loadNode(index);
          break;

        case "mesh":
          dependency = this._invokeOne(function (ext) {
            return ext.loadMesh && ext.loadMesh(index);
          });
          break;

        case "accessor":
          dependency = this.loadAccessor(index);
          break;

        case "bufferView":
          dependency = this._invokeOne(function (ext) {
            return ext.loadBufferView && ext.loadBufferView(index);
          });
          break;

        case "buffer":
          dependency = this.loadBuffer(index);
          break;

        case "material":
          dependency = this._invokeOne(function (ext) {
            return ext.loadMaterial && ext.loadMaterial(index);
          });
          break;

        case "texture":
          dependency = this._invokeOne(function (ext) {
            return ext.loadTexture && ext.loadTexture(index);
          });
          break;

        case "skin":
          dependency = this.loadSkin(index);
          break;

        case "animation":
          dependency = this._invokeOne(function (ext) {
            return ext.loadAnimation && ext.loadAnimation(index);
          });
          break;

        case "camera":
          dependency = this.loadCamera(index);
          break;

        default:
          dependency = this._invokeOne(function (ext) {
            return (
              ext != this && ext.getDependency && ext.getDependency(type, index)
            );
          });

          if (!dependency) {
            throw new Error("Unknown type: " + type);
          }

          break;
      }

      this.cache.add(cacheKey, dependency);
    }

    return dependency;
  }

  /**
   * Requests all dependencies of the specified type asynchronously, with caching.
   * @param {string} type
   * @return {Promise<Array<Object>>}
   */
  getDependencies(type) {
    let dependencies = this.cache.get(type);

    if (!dependencies) {
      const parser = this;
      const defs = this.json[type + (type === "mesh" ? "es" : "s")] || [];

      dependencies = Promise.all(
        defs.map(function (def, index) {
          return parser.getDependency(type, index);
        })
      );

      this.cache.add(type, dependencies);
    }

    return dependencies;
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
   * @param {number} bufferIndex
   * @return {Promise<ArrayBuffer>}
   */
  loadBuffer(bufferIndex) {
    const bufferDef = this.json.buffers[bufferIndex];
    const loader = this.fileLoader;

    if (bufferDef.type && bufferDef.type !== "arraybuffer") {
      throw new Error(
        "THREE.GLTFLoader: " + bufferDef.type + " buffer type is not supported."
      );
    }

    // If present, GLB container is required to be the first buffer.
    if (bufferDef.uri === undefined && bufferIndex === 0) {
      return Promise.resolve(this.extensions[EXTENSIONS.KHR_BINARY_GLTF].body);
    }

    const options = this.options;

    return new Promise(function (resolve, reject) {
      loader.load(
        LoaderUtils.resolveURL(bufferDef.uri, options.path),
        resolve,
        undefined,
        function () {
          reject(
            new Error(
              'THREE.GLTFLoader: Failed to load buffer "' + bufferDef.uri + '".'
            )
          );
        }
      );
    });
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#buffers-and-buffer-views
   * @param {number} bufferViewIndex
   * @return {Promise<ArrayBuffer>}
   */
  loadBufferView(bufferViewIndex) {
    const bufferViewDef = this.json.bufferViews[bufferViewIndex];

    return this.getDependency("buffer", bufferViewDef.buffer).then(function (
      buffer
    ) {
      const byteLength = bufferViewDef.byteLength || 0;
      const byteOffset = bufferViewDef.byteOffset || 0;
      return buffer.slice(byteOffset, byteOffset + byteLength);
    });
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#accessors
   * @param {number} accessorIndex
   * @return {Promise<BufferAttribute|InterleavedBufferAttribute>}
   */
  loadAccessor(accessorIndex) {
    const parser = this;
    const json = this.json;

    const accessorDef = this.json.accessors[accessorIndex];

    if (
      accessorDef.bufferView === undefined &&
      accessorDef.sparse === undefined
    ) {
      const itemSize = WEBGL_TYPE_SIZES[accessorDef.type];
      const TypedArray = WEBGL_COMPONENT_TYPES[accessorDef.componentType];
      const normalized = accessorDef.normalized === true;

      const array = new TypedArray(accessorDef.count * itemSize);
      return Promise.resolve(new BufferAttribute(array, itemSize, normalized));
    }

    const pendingBufferViews = [];

    if (accessorDef.bufferView !== undefined) {
      pendingBufferViews.push(
        this.getDependency("bufferView", accessorDef.bufferView)
      );
    } else {
      pendingBufferViews.push(null);
    }

    if (accessorDef.sparse !== undefined) {
      pendingBufferViews.push(
        this.getDependency("bufferView", accessorDef.sparse.indices.bufferView)
      );
      pendingBufferViews.push(
        this.getDependency("bufferView", accessorDef.sparse.values.bufferView)
      );
    }

    return Promise.all(pendingBufferViews).then(function (bufferViews) {
      const bufferView = bufferViews[0];

      const itemSize = WEBGL_TYPE_SIZES[accessorDef.type];
      const TypedArray = WEBGL_COMPONENT_TYPES[accessorDef.componentType];

      // For VEC3: itemSize is 3, elementBytes is 4, itemBytes is 12.
      const elementBytes = TypedArray.BYTES_PER_ELEMENT;
      const itemBytes = elementBytes * itemSize;
      const byteOffset = accessorDef.byteOffset || 0;
      const byteStride =
        accessorDef.bufferView !== undefined
          ? json.bufferViews[accessorDef.bufferView].byteStride
          : undefined;
      const normalized = accessorDef.normalized === true;
      let array, bufferAttribute;

      // The buffer is not interleaved if the stride is the item size in bytes.
      if (byteStride && byteStride !== itemBytes) {
        // Each "slice" of the buffer, as defined by 'count' elements of 'byteStride' bytes, gets its own InterleavedBuffer
        // This makes sure that IBA.count reflects accessor.count properly
        const ibSlice = Math.floor(byteOffset / byteStride);
        const ibCacheKey =
          "InterleavedBuffer:" +
          accessorDef.bufferView +
          ":" +
          accessorDef.componentType +
          ":" +
          ibSlice +
          ":" +
          accessorDef.count;
        let ib = parser.cache.get(ibCacheKey);

        if (!ib) {
          array = new TypedArray(
            bufferView,
            ibSlice * byteStride,
            (accessorDef.count * byteStride) / elementBytes
          );

          // Integer parameters to IB/IBA are in array elements, not bytes.
          ib = new InterleavedBuffer(array, byteStride / elementBytes);

          parser.cache.add(ibCacheKey, ib);
        }

        bufferAttribute = new InterleavedBufferAttribute(
          ib,
          itemSize,
          (byteOffset % byteStride) / elementBytes,
          normalized
        );
      } else {
        if (bufferView === null) {
          array = new TypedArray(accessorDef.count * itemSize);
        } else {
          array = new TypedArray(
            bufferView,
            byteOffset,
            accessorDef.count * itemSize
          );
        }

        bufferAttribute = new BufferAttribute(array, itemSize, normalized);
      }

      // https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#sparse-accessors
      if (accessorDef.sparse !== undefined) {
        const itemSizeIndices = WEBGL_TYPE_SIZES.SCALAR;
        const TypedArrayIndices =
          WEBGL_COMPONENT_TYPES[accessorDef.sparse.indices.componentType];

        const byteOffsetIndices = accessorDef.sparse.indices.byteOffset || 0;
        const byteOffsetValues = accessorDef.sparse.values.byteOffset || 0;

        const sparseIndices = new TypedArrayIndices(
          bufferViews[1],
          byteOffsetIndices,
          accessorDef.sparse.count * itemSizeIndices
        );
        const sparseValues = new TypedArray(
          bufferViews[2],
          byteOffsetValues,
          accessorDef.sparse.count * itemSize
        );

        if (bufferView !== null) {
          // Avoid modifying the original ArrayBuffer, if the bufferView wasn't initialized with zeroes.
          bufferAttribute = new BufferAttribute(
            bufferAttribute.array.slice(),
            bufferAttribute.itemSize,
            bufferAttribute.normalized
          );
        }

        for (let i = 0, il = sparseIndices.length; i < il; i++) {
          const index = sparseIndices[i];

          bufferAttribute.setX(index, sparseValues[i * itemSize]);
          if (itemSize >= 2)
            bufferAttribute.setY(index, sparseValues[i * itemSize + 1]);
          if (itemSize >= 3)
            bufferAttribute.setZ(index, sparseValues[i * itemSize + 2]);
          if (itemSize >= 4)
            bufferAttribute.setW(index, sparseValues[i * itemSize + 3]);
          if (itemSize >= 5)
            throw new Error(
              "THREE.GLTFLoader: Unsupported itemSize in sparse BufferAttribute."
            );
        }
      }

      return bufferAttribute;
    });
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#textures
   * @param {number} textureIndex
   * @return {Promise<THREE.Texture|null>}
   */
  loadTexture(textureIndex) {
    const json = this.json;
    const options = this.options;
    const textureDef = json.textures[textureIndex];
    const sourceIndex = textureDef.source;
    const sourceDef = json.images[sourceIndex];

    let loader = this.textureLoader;

    if (sourceDef.uri) {
      const handler = options.manager.getHandler(sourceDef.uri);
      if (handler !== null) loader = handler;
    }

    return this.loadTextureImage(textureIndex, sourceIndex, loader);
  }

  loadTextureImage(textureIndex, sourceIndex, loader) {
    const parser = this;
    const json = this.json;

    const textureDef = json.textures[textureIndex];
    const sourceDef = json.images[sourceIndex];

    const cacheKey =
      (sourceDef.uri || sourceDef.bufferView) + ":" + textureDef.sampler;

    if (this.textureCache[cacheKey]) {
      // See https://github.com/mrdoob/three.js/issues/21559.
      return this.textureCache[cacheKey];
    }

    const promise = this.loadImageSource(sourceIndex, loader)
      .then(function (texture) {
        texture.flipY = false;

        texture.name = textureDef.name || sourceDef.name || "";

        const samplers = json.samplers || {};
        const sampler = samplers[textureDef.sampler] || {};

        texture.magFilter = WEBGL_FILTERS[sampler.magFilter] || LinearFilter;
        texture.minFilter =
          WEBGL_FILTERS[sampler.minFilter] || LinearMipmapLinearFilter;
        texture.wrapS = WEBGL_WRAPPINGS[sampler.wrapS] || RepeatWrapping;
        texture.wrapT = WEBGL_WRAPPINGS[sampler.wrapT] || RepeatWrapping;

        parser.associations.set(texture, { textures: textureIndex });

        return texture;
      })
      .catch(function () {
        return null;
      });

    this.textureCache[cacheKey] = promise;

    return promise;
  }

  loadImageSource(sourceIndex, loader) {
    const parser = this;
    const json = this.json;
    const options = this.options;

    if (this.sourceCache[sourceIndex] !== undefined) {
      return this.sourceCache[sourceIndex].then((texture) => texture.clone());
    }

    const sourceDef = json.images[sourceIndex];

    const URL = self.URL || self.webkitURL;

    let sourceURI = sourceDef.uri || "";
    let isObjectURL = false;

    if (sourceDef.bufferView !== undefined) {
      // Load binary image data from bufferView, if provided.

      sourceURI = parser
        .getDependency("bufferView", sourceDef.bufferView)
        .then(function (bufferView) {
          isObjectURL = true;
          const blob = new Blob([bufferView], { type: sourceDef.mimeType });
          sourceURI = URL.createObjectURL(blob);
          return sourceURI;
        });
    } else if (sourceDef.uri === undefined) {
      throw new Error(
        "THREE.GLTFLoader: Image " +
          sourceIndex +
          " is missing URI and bufferView"
      );
    }

    const promise = Promise.resolve(sourceURI)
      .then(function (sourceURI) {
        return new Promise(function (resolve, reject) {
          let onLoad = resolve;

          if (loader.isImageBitmapLoader === true) {
            onLoad = function (imageBitmap) {
              const texture = new Texture(imageBitmap);
              texture.needsUpdate = true;

              resolve(texture);
            };
          }

          loader.load(
            LoaderUtils.resolveURL(sourceURI, options.path),
            onLoad,
            undefined,
            reject
          );
        });
      })
      .then(function (texture) {
        // Clean up resources and configure Texture.

        if (isObjectURL === true) {
          URL.revokeObjectURL(sourceURI);
        }

        texture.userData.mimeType =
          sourceDef.mimeType || getImageURIMimeType(sourceDef.uri);

        return texture;
      })
      .catch(function (error) {
        console.error("THREE.GLTFLoader: Couldn't load texture", sourceURI);
        throw error;
      });

    this.sourceCache[sourceIndex] = promise;
    return promise;
  }

  /**
   * Asynchronously assigns a texture to the given material parameters.
   * @param {Object} materialParams
   * @param {string} mapName
   * @param {Object} mapDef
   * @return {Promise<Texture>}
   */
  assignTexture(materialParams, mapName, mapDef, encoding) {
    const parser = this;

    return this.getDependency("texture", mapDef.index).then(function (texture) {
      if (!texture) return null;

      // Materials sample aoMap from UV set 1 and other maps from UV set 0 - this can't be configured
      // However, we will copy UV set 0 to UV set 1 on demand for aoMap
      if (
        mapDef.texCoord !== undefined &&
        mapDef.texCoord != 0 &&
        !(mapName === "aoMap" && mapDef.texCoord == 1)
      ) {
        console.warn(
          "THREE.GLTFLoader: Custom UV set " +
            mapDef.texCoord +
            " for texture " +
            mapName +
            " not yet supported."
        );
      }

      if (parser.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]) {
        const transform =
          mapDef.extensions !== undefined
            ? mapDef.extensions[EXTENSIONS.KHR_TEXTURE_TRANSFORM]
            : undefined;

        if (transform) {
          const gltfReference = parser.associations.get(texture);
          texture = parser.extensions[
            EXTENSIONS.KHR_TEXTURE_TRANSFORM
          ].extendTexture(texture, transform);
          parser.associations.set(texture, gltfReference);
        }
      }

      if (encoding !== undefined) {
        texture.encoding = encoding;
      }

      materialParams[mapName] = texture;

      return texture;
    });
  }

  /**
   * Assigns final material to a Mesh, Line, or Points instance. The instance
   * already has a material (generated from the glTF material options alone)
   * but reuse of the same glTF material may require multiple threejs materials
   * to accommodate different primitive types, defines, etc. New materials will
   * be created if necessary, and reused from a cache.
   * @param  {Object3D} mesh Mesh, Line, or Points instance.
   */
  assignFinalMaterial(mesh) {
    const geometry = mesh.geometry;
    let material = mesh.material;

    const useDerivativeTangents = geometry.attributes.tangent === undefined;
    const useVertexColors = geometry.attributes.color !== undefined;
    const useFlatShading = geometry.attributes.normal === undefined;

    if (mesh.isPoints) {
      const cacheKey = "PointsMaterial:" + material.uuid;

      let pointsMaterial = this.cache.get(cacheKey);

      if (!pointsMaterial) {
        pointsMaterial = new PointsMaterial();
        Material.prototype.copy.call(pointsMaterial, material);
        pointsMaterial.color.copy(material.color);
        pointsMaterial.map = material.map;
        pointsMaterial.sizeAttenuation = false; // glTF spec says points should be 1px

        this.cache.add(cacheKey, pointsMaterial);
      }

      material = pointsMaterial;
    } else if (mesh.isLine) {
      const cacheKey = "LineBasicMaterial:" + material.uuid;

      let lineMaterial = this.cache.get(cacheKey);

      if (!lineMaterial) {
        lineMaterial = new LineBasicMaterial();
        Material.prototype.copy.call(lineMaterial, material);
        lineMaterial.color.copy(material.color);

        this.cache.add(cacheKey, lineMaterial);
      }

      material = lineMaterial;
    }

    // Clone the material if it will be modified
    if (useDerivativeTangents || useVertexColors || useFlatShading) {
      let cacheKey = "ClonedMaterial:" + material.uuid + ":";

      if (useDerivativeTangents) cacheKey += "derivative-tangents:";
      if (useVertexColors) cacheKey += "vertex-colors:";
      if (useFlatShading) cacheKey += "flat-shading:";

      let cachedMaterial = this.cache.get(cacheKey);

      if (!cachedMaterial) {
        cachedMaterial = material.clone();

        if (useVertexColors) cachedMaterial.vertexColors = true;
        if (useFlatShading) cachedMaterial.flatShading = true;

        if (useDerivativeTangents) {
          // https://github.com/mrdoob/three.js/issues/11438#issuecomment-507003995
          if (cachedMaterial.normalScale) cachedMaterial.normalScale.y *= -1;
          if (cachedMaterial.clearcoatNormalScale)
            cachedMaterial.clearcoatNormalScale.y *= -1;
        }

        this.cache.add(cacheKey, cachedMaterial);

        this.associations.set(cachedMaterial, this.associations.get(material));
      }

      material = cachedMaterial;
    }

    // workarounds for mesh and geometry

    if (
      material.aoMap &&
      geometry.attributes.uv2 === undefined &&
      geometry.attributes.uv !== undefined
    ) {
      geometry.setAttribute("uv2", geometry.attributes.uv);
    }

    mesh.material = material;
  }

  getMaterialType(/* materialIndex */) {
    return MeshStandardMaterial;
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#materials
   * @param {number} materialIndex
   * @return {Promise<Material>}
   */
  loadMaterial(materialIndex) {
    const parser = this;
    const json = this.json;
    const extensions = this.extensions;
    const materialDef = json.materials[materialIndex];

    let materialType;
    const materialParams = {};
    const materialExtensions = materialDef.extensions || {};

    const pending = [];

    if (materialExtensions[EXTENSIONS.KHR_MATERIALS_UNLIT]) {
      const kmuExtension = extensions[EXTENSIONS.KHR_MATERIALS_UNLIT];
      materialType = kmuExtension.getMaterialType();
      pending.push(
        kmuExtension.extendParams(materialParams, materialDef, parser)
      );
    } else {
      // Specification:
      // https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#metallic-roughness-material

      const metallicRoughness = materialDef.pbrMetallicRoughness || {};

      materialParams.color = new Color(1.0, 1.0, 1.0);
      materialParams.opacity = 1.0;

      if (Array.isArray(metallicRoughness.baseColorFactor)) {
        const array = metallicRoughness.baseColorFactor;

        materialParams.color.fromArray(array);
        materialParams.opacity = array[3];
      }

      if (metallicRoughness.baseColorTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "map",
            metallicRoughness.baseColorTexture,
            sRGBEncoding
          )
        );
      }

      materialParams.metalness =
        metallicRoughness.metallicFactor !== undefined
          ? metallicRoughness.metallicFactor
          : 1.0;
      materialParams.roughness =
        metallicRoughness.roughnessFactor !== undefined
          ? metallicRoughness.roughnessFactor
          : 1.0;

      if (metallicRoughness.metallicRoughnessTexture !== undefined) {
        pending.push(
          parser.assignTexture(
            materialParams,
            "metalnessMap",
            metallicRoughness.metallicRoughnessTexture
          )
        );
        pending.push(
          parser.assignTexture(
            materialParams,
            "roughnessMap",
            metallicRoughness.metallicRoughnessTexture
          )
        );
      }

      materialType = this._invokeOne(function (ext) {
        return ext.getMaterialType && ext.getMaterialType(materialIndex);
      });

      pending.push(
        Promise.all(
          this._invokeAll(function (ext) {
            return (
              ext.extendMaterialParams &&
              ext.extendMaterialParams(materialIndex, materialParams)
            );
          })
        )
      );
    }

    if (materialDef.doubleSided === true) {
      materialParams.side = DoubleSide;
    }

    const alphaMode = materialDef.alphaMode || ALPHA_MODES.OPAQUE;

    if (alphaMode === ALPHA_MODES.BLEND) {
      materialParams.transparent = true;

      // See: https://github.com/mrdoob/three.js/issues/17706
      materialParams.depthWrite = false;
    } else {
      materialParams.transparent = false;

      if (alphaMode === ALPHA_MODES.MASK) {
        materialParams.alphaTest =
          materialDef.alphaCutoff !== undefined ? materialDef.alphaCutoff : 0.5;
      }
    }

    if (
      materialDef.normalTexture !== undefined &&
      materialType !== MeshBasicMaterial
    ) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "normalMap",
          materialDef.normalTexture
        )
      );

      materialParams.normalScale = new Vector2(1, 1);

      if (materialDef.normalTexture.scale !== undefined) {
        const scale = materialDef.normalTexture.scale;

        materialParams.normalScale.set(scale, scale);
      }
    }

    if (
      materialDef.occlusionTexture !== undefined &&
      materialType !== MeshBasicMaterial
    ) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "aoMap",
          materialDef.occlusionTexture
        )
      );

      if (materialDef.occlusionTexture.strength !== undefined) {
        materialParams.aoMapIntensity = materialDef.occlusionTexture.strength;
      }
    }

    if (
      materialDef.emissiveFactor !== undefined &&
      materialType !== MeshBasicMaterial
    ) {
      materialParams.emissive = new Color().fromArray(
        materialDef.emissiveFactor
      );
    }

    if (
      materialDef.emissiveTexture !== undefined &&
      materialType !== MeshBasicMaterial
    ) {
      pending.push(
        parser.assignTexture(
          materialParams,
          "emissiveMap",
          materialDef.emissiveTexture,
          sRGBEncoding
        )
      );
    }

    return Promise.all(pending).then(function () {
      const material = new materialType(materialParams);

      if (materialDef.name) material.name = materialDef.name;

      assignExtrasToUserData(material, materialDef);

      parser.associations.set(material, { materials: materialIndex });

      if (materialDef.extensions)
        addUnknownExtensionsToUserData(extensions, material, materialDef);

      return material;
    });
  }

  /** When Object3D instances are targeted by animation, they need unique names. */
  createUniqueName(originalName) {
    const sanitizedName = PropertyBinding.sanitizeNodeName(originalName || "");

    let name = sanitizedName;

    for (let i = 1; this.nodeNamesUsed[name]; ++i) {
      name = sanitizedName + "_" + i;
    }

    this.nodeNamesUsed[name] = true;

    return name;
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#geometry
   *
   * Creates BufferGeometries from primitives.
   *
   * @param {Array<GLTF.Primitive>} primitives
   * @return {Promise<Array<BufferGeometry>>}
   */
  loadGeometries(primitives) {
    const parser = this;
    const extensions = this.extensions;
    const cache = this.primitiveCache;

    function createDracoPrimitive(primitive) {
      return extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
        .decodePrimitive(primitive, parser)
        .then(function (geometry) {
          return addPrimitiveAttributes(geometry, primitive, parser);
        });
    }

    const pending = [];

    for (let i = 0, il = primitives.length; i < il; i++) {
      const primitive = primitives[i];
      const cacheKey = createPrimitiveKey(primitive);

      // See if we've already created this geometry
      const cached = cache[cacheKey];

      if (cached) {
        // Use the cached geometry if it exists
        pending.push(cached.promise);
      } else {
        let geometryPromise;

        if (
          primitive.extensions &&
          primitive.extensions[EXTENSIONS.KHR_DRACO_MESH_COMPRESSION]
        ) {
          // Use DRACO geometry if available
          geometryPromise = createDracoPrimitive(primitive);
        } else {
          // Otherwise create a new geometry
          geometryPromise = addPrimitiveAttributes(
            new BufferGeometry(),
            primitive,
            parser
          );
        }

        // Cache this geometry
        cache[cacheKey] = { primitive: primitive, promise: geometryPromise };

        pending.push(geometryPromise);
      }
    }

    return Promise.all(pending);
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/blob/master/specification/2.0/README.md#meshes
   * @param {number} meshIndex
   * @return {Promise<Group|Mesh|SkinnedMesh>}
   */
  loadMesh(meshIndex) {
    const parser = this;
    const json = this.json;
    const extensions = this.extensions;

    const meshDef = json.meshes[meshIndex];
    const primitives = meshDef.primitives;

    const pending = [];

    for (let i = 0, il = primitives.length; i < il; i++) {
      const material =
        primitives[i].material === undefined
          ? createDefaultMaterial(this.cache)
          : this.getDependency("material", primitives[i].material);

      pending.push(material);
    }

    pending.push(parser.loadGeometries(primitives));

    return Promise.all(pending).then(function (results) {
      const materials = results.slice(0, results.length - 1);
      const geometries = results[results.length - 1];

      const meshes = [];

      for (let i = 0, il = geometries.length; i < il; i++) {
        const geometry = geometries[i];
        const primitive = primitives[i];

        // 1. create Mesh

        let mesh;

        const material = materials[i];

        if (
          primitive.mode === WEBGL_CONSTANTS.TRIANGLES ||
          primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP ||
          primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN ||
          primitive.mode === undefined
        ) {
          // .isSkinnedMesh isn't in glTF spec. See ._markDefs()
          mesh =
            meshDef.isSkinnedMesh === true
              ? new SkinnedMesh(geometry, material)
              : new Mesh(geometry, material);

          if (
            mesh.isSkinnedMesh === true &&
            !mesh.geometry.attributes.skinWeight.normalized
          ) {
            // we normalize floating point skin weight array to fix malformed assets (see #15319)
            // it's important to skip this for non-float32 data since normalizeSkinWeights assumes non-normalized inputs
            mesh.normalizeSkinWeights();
          }

          if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_STRIP) {
            mesh.geometry = toTrianglesDrawMode(
              mesh.geometry,
              TriangleStripDrawMode
            );
          } else if (primitive.mode === WEBGL_CONSTANTS.TRIANGLE_FAN) {
            mesh.geometry = toTrianglesDrawMode(
              mesh.geometry,
              TriangleFanDrawMode
            );
          }
        } else if (primitive.mode === WEBGL_CONSTANTS.LINES) {
          mesh = new LineSegments(geometry, material);
        } else if (primitive.mode === WEBGL_CONSTANTS.LINE_STRIP) {
          mesh = new Line(geometry, material);
        } else if (primitive.mode === WEBGL_CONSTANTS.LINE_LOOP) {
          mesh = new LineLoop(geometry, material);
        } else if (primitive.mode === WEBGL_CONSTANTS.POINTS) {
          mesh = new Points(geometry, material);
        } else {
          throw new Error(
            "THREE.GLTFLoader: Primitive mode unsupported: " + primitive.mode
          );
        }

        if (Object.keys(mesh.geometry.morphAttributes).length > 0) {
          updateMorphTargets(mesh, meshDef);
        }

        mesh.name = parser.createUniqueName(
          meshDef.name || "mesh_" + meshIndex
        );

        assignExtrasToUserData(mesh, meshDef);

        if (primitive.extensions)
          addUnknownExtensionsToUserData(extensions, mesh, primitive);

        parser.assignFinalMaterial(mesh);

        meshes.push(mesh);
      }

      for (let i = 0, il = meshes.length; i < il; i++) {
        parser.associations.set(meshes[i], {
          meshes: meshIndex,
          primitives: i,
        });
      }

      if (meshes.length === 1) {
        return meshes[0];
      }

      const group = new Group();

      parser.associations.set(group, { meshes: meshIndex });

      for (let i = 0, il = meshes.length; i < il; i++) {
        group.add(meshes[i]);
      }

      return group;
    });
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#cameras
   * @param {number} cameraIndex
   * @return {Promise<THREE.Camera>}
   */
  loadCamera(cameraIndex) {
    let camera;
    const cameraDef = this.json.cameras[cameraIndex];
    const params = cameraDef[cameraDef.type];

    if (!params) {
      console.warn("THREE.GLTFLoader: Missing camera parameters.");
      return;
    }

    if (cameraDef.type === "perspective") {
      camera = new PerspectiveCamera(
        MathUtils.radToDeg(params.yfov),
        params.aspectRatio || 1,
        params.znear || 1,
        params.zfar || 2e6
      );
    } else if (cameraDef.type === "orthographic") {
      camera = new OrthographicCamera(
        -params.xmag,
        params.xmag,
        params.ymag,
        -params.ymag,
        params.znear,
        params.zfar
      );
    }

    if (cameraDef.name) camera.name = this.createUniqueName(cameraDef.name);

    assignExtrasToUserData(camera, cameraDef);

    return Promise.resolve(camera);
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#skins
   * @param {number} skinIndex
   * @return {Promise<Skeleton>}
   */
  loadSkin(skinIndex) {
    const skinDef = this.json.skins[skinIndex];

    const pending = [];

    for (let i = 0, il = skinDef.joints.length; i < il; i++) {
      pending.push(this.getDependency("node", skinDef.joints[i]));
    }

    if (skinDef.inverseBindMatrices !== undefined) {
      pending.push(this.getDependency("accessor", skinDef.inverseBindMatrices));
    } else {
      pending.push(null);
    }

    return Promise.all(pending).then(function (results) {
      const inverseBindMatrices = results.pop();
      const jointNodes = results;

      const bones = [];
      const boneInverses = [];

      for (let i = 0, il = jointNodes.length; i < il; i++) {
        const jointNode = jointNodes[i];

        if (jointNode) {
          bones.push(jointNode);

          const mat = new Matrix4();

          if (inverseBindMatrices !== null) {
            mat.fromArray(inverseBindMatrices.array, i * 16);
          }

          boneInverses.push(mat);
        } else {
          console.warn(
            'THREE.GLTFLoader: Joint "%s" could not be found.',
            skinDef.joints[i]
          );
        }
      }

      return new Skeleton(bones, boneInverses);
    });
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#animations
   * @param {number} animationIndex
   * @return {Promise<AnimationClip>}
   */
  loadAnimation(animationIndex) {
    const json = this.json;

    const animationDef = json.animations[animationIndex];

    const pendingNodes = [];
    const pendingInputAccessors = [];
    const pendingOutputAccessors = [];
    const pendingSamplers = [];
    const pendingTargets = [];

    for (let i = 0, il = animationDef.channels.length; i < il; i++) {
      const channel = animationDef.channels[i];
      const sampler = animationDef.samplers[channel.sampler];
      const target = channel.target;
      const name = target.node;
      const input =
        animationDef.parameters !== undefined
          ? animationDef.parameters[sampler.input]
          : sampler.input;
      const output =
        animationDef.parameters !== undefined
          ? animationDef.parameters[sampler.output]
          : sampler.output;

      pendingNodes.push(this.getDependency("node", name));
      pendingInputAccessors.push(this.getDependency("accessor", input));
      pendingOutputAccessors.push(this.getDependency("accessor", output));
      pendingSamplers.push(sampler);
      pendingTargets.push(target);
    }

    return Promise.all([
      Promise.all(pendingNodes),
      Promise.all(pendingInputAccessors),
      Promise.all(pendingOutputAccessors),
      Promise.all(pendingSamplers),
      Promise.all(pendingTargets),
    ]).then(function (dependencies) {
      const nodes = dependencies[0];
      const inputAccessors = dependencies[1];
      const outputAccessors = dependencies[2];
      const samplers = dependencies[3];
      const targets = dependencies[4];

      const tracks = [];

      for (let i = 0, il = nodes.length; i < il; i++) {
        const node = nodes[i];
        const inputAccessor = inputAccessors[i];
        const outputAccessor = outputAccessors[i];
        const sampler = samplers[i];
        const target = targets[i];

        if (node === undefined) continue;

        node.updateMatrix();

        let TypedKeyframeTrack;

        switch (PATH_PROPERTIES[target.path]) {
          case PATH_PROPERTIES.weights:
            TypedKeyframeTrack = NumberKeyframeTrack;
            break;

          case PATH_PROPERTIES.rotation:
            TypedKeyframeTrack = QuaternionKeyframeTrack;
            break;

          case PATH_PROPERTIES.position:
          case PATH_PROPERTIES.scale:
          default:
            TypedKeyframeTrack = VectorKeyframeTrack;
            break;
        }

        const targetName = node.name ? node.name : node.uuid;

        const interpolation =
          sampler.interpolation !== undefined
            ? INTERPOLATION[sampler.interpolation]
            : InterpolateLinear;

        const targetNames = [];

        if (PATH_PROPERTIES[target.path] === PATH_PROPERTIES.weights) {
          node.traverse(function (object) {
            if (object.morphTargetInfluences) {
              targetNames.push(object.name ? object.name : object.uuid);
            }
          });
        } else {
          targetNames.push(targetName);
        }

        let outputArray = outputAccessor.array;

        if (outputAccessor.normalized) {
          const scale = getNormalizedComponentScale(outputArray.constructor);
          const scaled = new Float32Array(outputArray.length);

          for (let j = 0, jl = outputArray.length; j < jl; j++) {
            scaled[j] = outputArray[j] * scale;
          }

          outputArray = scaled;
        }

        for (let j = 0, jl = targetNames.length; j < jl; j++) {
          const track = new TypedKeyframeTrack(
            targetNames[j] + "." + PATH_PROPERTIES[target.path],
            inputAccessor.array,
            outputArray,
            interpolation
          );

          // Override interpolation with custom factory method.
          if (sampler.interpolation === "CUBICSPLINE") {
            track.createInterpolant =
              function InterpolantFactoryMethodGLTFCubicSpline(result) {
                // A CUBICSPLINE keyframe in glTF has three output values for each input value,
                // representing inTangent, splineVertex, and outTangent. As a result, track.getValueSize()
                // must be divided by three to get the interpolant's sampleSize argument.

                const interpolantType =
                  this instanceof QuaternionKeyframeTrack
                    ? GLTFCubicSplineQuaternionInterpolant
                    : GLTFCubicSplineInterpolant;

                return new interpolantType(
                  this.times,
                  this.values,
                  this.getValueSize() / 3,
                  result
                );
              };

            // Mark as CUBICSPLINE. `track.getInterpolation()` doesn't support custom interpolants.
            track.createInterpolant.isInterpolantFactoryMethodGLTFCubicSpline = true;
          }

          tracks.push(track);
        }
      }

      const name = animationDef.name
        ? animationDef.name
        : "animation_" + animationIndex;

      return new AnimationClip(name, undefined, tracks);
    });
  }

  createNodeMesh(nodeIndex) {
    const json = this.json;
    const parser = this;
    const nodeDef = json.nodes[nodeIndex];

    if (nodeDef.mesh === undefined) return null;

    return parser.getDependency("mesh", nodeDef.mesh).then(function (mesh) {
      const node = parser._getNodeRef(parser.meshCache, nodeDef.mesh, mesh);

      // if weights are provided on the node, override weights on the mesh.
      if (nodeDef.weights !== undefined) {
        node.traverse(function (o) {
          if (!o.isMesh) return;

          for (let i = 0, il = nodeDef.weights.length; i < il; i++) {
            o.morphTargetInfluences[i] = nodeDef.weights[i];
          }
        });
      }

      return node;
    });
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#nodes-and-hierarchy
   * @param {number} nodeIndex
   * @return {Promise<Object3D>}
   */
  loadNode(nodeIndex) {
    const json = this.json;
    const extensions = this.extensions;
    const parser = this;

    const nodeDef = json.nodes[nodeIndex];

    // reserve node's name before its dependencies, so the root has the intended name.
    const nodeName = nodeDef.name ? parser.createUniqueName(nodeDef.name) : "";

    return (function () {
      const pending = [];

      const meshPromise = parser._invokeOne(function (ext) {
        return ext.createNodeMesh && ext.createNodeMesh(nodeIndex);
      });

      if (meshPromise) {
        pending.push(meshPromise);
      }

      if (nodeDef.camera !== undefined) {
        pending.push(
          parser
            .getDependency("camera", nodeDef.camera)
            .then(function (camera) {
              return parser._getNodeRef(
                parser.cameraCache,
                nodeDef.camera,
                camera
              );
            })
        );
      }

      parser
        ._invokeAll(function (ext) {
          return (
            ext.createNodeAttachment && ext.createNodeAttachment(nodeIndex)
          );
        })
        .forEach(function (promise) {
          pending.push(promise);
        });

      return Promise.all(pending);
    })().then(function (objects) {
      let node;

      // .isBone isn't in glTF spec. See ._markDefs
      if (nodeDef.isBone === true) {
        node = new Bone();
      } else if (objects.length > 1) {
        node = new Group();
      } else if (objects.length === 1) {
        node = objects[0];
      } else {
        node = new Object3D();
      }

      if (node !== objects[0]) {
        for (let i = 0, il = objects.length; i < il; i++) {
          node.add(objects[i]);
        }
      }

      if (nodeDef.name) {
        node.userData.name = nodeDef.name;
        node.name = nodeName;
      }

      assignExtrasToUserData(node, nodeDef);

      if (nodeDef.extensions)
        addUnknownExtensionsToUserData(extensions, node, nodeDef);

      if (nodeDef.matrix !== undefined) {
        const matrix = new Matrix4();
        matrix.fromArray(nodeDef.matrix);
        node.applyMatrix4(matrix);
      } else {
        if (nodeDef.translation !== undefined) {
          node.position.fromArray(nodeDef.translation);
        }

        if (nodeDef.rotation !== undefined) {
          node.quaternion.fromArray(nodeDef.rotation);
        }

        if (nodeDef.scale !== undefined) {
          node.scale.fromArray(nodeDef.scale);
        }
      }

      if (!parser.associations.has(node)) {
        parser.associations.set(node, {});
      }

      parser.associations.get(node).nodes = nodeIndex;

      return node;
    });
  }

  /**
   * Specification: https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#scenes
   * @param {number} sceneIndex
   * @return {Promise<Group>}
   */
  loadScene(sceneIndex) {
    const json = this.json;
    const extensions = this.extensions;
    const sceneDef = this.json.scenes[sceneIndex];
    const parser = this;

    // Loader returns Group, not Scene.
    // See: https://github.com/mrdoob/three.js/issues/18342#issuecomment-578981172
    const scene = new Group();
    if (sceneDef.name) scene.name = parser.createUniqueName(sceneDef.name);

    assignExtrasToUserData(scene, sceneDef);

    if (sceneDef.extensions)
      addUnknownExtensionsToUserData(extensions, scene, sceneDef);

    const nodeIds = sceneDef.nodes || [];

    const pending = [];

    for (let i = 0, il = nodeIds.length; i < il; i++) {
      pending.push(buildNodeHierarchy(nodeIds[i], scene, json, parser));
    }

    return Promise.all(pending).then(function () {
      // Removes dangling associations, associations that reference a node that
      // didn't make it into the scene.
      const reduceAssociations = (node) => {
        const reducedAssociations = new Map();

        for (const [key, value] of parser.associations) {
          if (key instanceof Material || key instanceof Texture) {
            reducedAssociations.set(key, value);
          }
        }

        node.traverse((node) => {
          const mappings = parser.associations.get(node);

          if (mappings != null) {
            reducedAssociations.set(node, mappings);
          }
        });

        return reducedAssociations;
      };

      parser.associations = reduceAssociations(scene);

      return scene;
    });
  }
}

function buildNodeHierarchy(nodeId, parentObject, json, parser) {
  const nodeDef = json.nodes[nodeId];

  return parser
    .getDependency("node", nodeId)
    .then(function (node) {
      if (nodeDef.skin === undefined) return node;

      // build skeleton here as well

      return parser
        .getDependency("skin", nodeDef.skin)
        .then(function (skeleton) {
          node.traverse(function (mesh) {
            if (!mesh.isSkinnedMesh) return;

            mesh.bind(skeleton, mesh.matrixWorld);
          });

          return node;
        });
    })
    .then(function (node) {
      // build node hierachy

      parentObject.add(node);

      const pending = [];

      if (nodeDef.children) {
        const children = nodeDef.children;

        for (let i = 0, il = children.length; i < il; i++) {
          const child = children[i];
          pending.push(buildNodeHierarchy(child, node, json, parser));
        }
      }

      return Promise.all(pending);
    });
}

/**
 * @param {BufferGeometry} geometry
 * @param {GLTF.Primitive} primitiveDef
 * @param {GLTFParser} parser
 */
function computeBounds(geometry, primitiveDef, parser) {
  const attributes = primitiveDef.attributes;

  const box = new Box3();

  if (attributes.POSITION !== undefined) {
    const accessor = parser.json.accessors[attributes.POSITION];

    const min = accessor.min;
    const max = accessor.max;

    // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

    if (min !== undefined && max !== undefined) {
      box.set(
        new Vector3(min[0], min[1], min[2]),
        new Vector3(max[0], max[1], max[2])
      );

      if (accessor.normalized) {
        const boxScale = getNormalizedComponentScale(
          WEBGL_COMPONENT_TYPES[accessor.componentType]
        );
        box.min.multiplyScalar(boxScale);
        box.max.multiplyScalar(boxScale);
      }
    } else {
      console.warn(
        "THREE.GLTFLoader: Missing min/max properties for accessor POSITION."
      );

      return;
    }
  } else {
    return;
  }

  const targets = primitiveDef.targets;

  if (targets !== undefined) {
    const maxDisplacement = new Vector3();
    const vector = new Vector3();

    for (let i = 0, il = targets.length; i < il; i++) {
      const target = targets[i];

      if (target.POSITION !== undefined) {
        const accessor = parser.json.accessors[target.POSITION];
        const min = accessor.min;
        const max = accessor.max;

        // glTF requires 'min' and 'max', but VRM (which extends glTF) currently ignores that requirement.

        if (min !== undefined && max !== undefined) {
          // we need to get max of absolute components because target weight is [-1,1]
          vector.setX(Math.max(Math.abs(min[0]), Math.abs(max[0])));
          vector.setY(Math.max(Math.abs(min[1]), Math.abs(max[1])));
          vector.setZ(Math.max(Math.abs(min[2]), Math.abs(max[2])));

          if (accessor.normalized) {
            const boxScale = getNormalizedComponentScale(
              WEBGL_COMPONENT_TYPES[accessor.componentType]
            );
            vector.multiplyScalar(boxScale);
          }

          // Note: this assumes that the sum of all weights is at most 1. This isn't quite correct - it's more conservative
          // to assume that each target can have a max weight of 1. However, for some use cases - notably, when morph targets
          // are used to implement key-frame animations and as such only two are active at a time - this results in very large
          // boxes. So for now we make a box that's sometimes a touch too small but is hopefully mostly of reasonable size.
          maxDisplacement.max(vector);
        } else {
          console.warn(
            "THREE.GLTFLoader: Missing min/max properties for accessor POSITION."
          );
        }
      }
    }

    // As per comment above this box isn't conservative, but has a reasonable size for a very large number of morph targets.
    box.expandByVector(maxDisplacement);
  }

  geometry.boundingBox = box;

  const sphere = new Sphere();

  box.getCenter(sphere.center);
  sphere.radius = box.min.distanceTo(box.max) / 2;

  geometry.boundingSphere = sphere;
}

/**
 * @param {BufferGeometry} geometry
 * @param {GLTF.Primitive} primitiveDef
 * @param {GLTFParser} parser
 * @return {Promise<BufferGeometry>}
 */
function addPrimitiveAttributes(geometry, primitiveDef, parser) {
  const attributes = primitiveDef.attributes;

  const pending = [];

  function assignAttributeAccessor(accessorIndex, attributeName) {
    return parser
      .getDependency("accessor", accessorIndex)
      .then(function (accessor) {
        geometry.setAttribute(attributeName, accessor);
      });
  }

  for (const gltfAttributeName in attributes) {
    const threeAttributeName =
      ATTRIBUTES[gltfAttributeName] || gltfAttributeName.toLowerCase();

    // Skip attributes already provided by e.g. Draco extension.
    if (threeAttributeName in geometry.attributes) continue;

    pending.push(
      assignAttributeAccessor(attributes[gltfAttributeName], threeAttributeName)
    );
  }

  if (primitiveDef.indices !== undefined && !geometry.index) {
    const accessor = parser
      .getDependency("accessor", primitiveDef.indices)
      .then(function (accessor) {
        geometry.setIndex(accessor);
      });

    pending.push(accessor);
  }

  assignExtrasToUserData(geometry, primitiveDef);

  computeBounds(geometry, primitiveDef, parser);

  return Promise.all(pending).then(function () {
    return primitiveDef.targets !== undefined
      ? addMorphTargets(geometry, primitiveDef.targets, parser)
      : geometry;
  });
}

/**
 * @param {BufferGeometry} geometry
 * @param {Number} drawMode
 * @return {BufferGeometry}
 */
function toTrianglesDrawMode(geometry, drawMode) {
  let index = geometry.getIndex();

  // generate index if not present

  if (index === null) {
    const indices = [];

    const position = geometry.getAttribute("position");

    if (position !== undefined) {
      for (let i = 0; i < position.count; i++) {
        indices.push(i);
      }

      geometry.setIndex(indices);
      index = geometry.getIndex();
    } else {
      console.error(
        "THREE.GLTFLoader.toTrianglesDrawMode(): Undefined position attribute. Processing not possible."
      );
      return geometry;
    }
  }

  //

  const numberOfTriangles = index.count - 2;
  const newIndices = [];

  if (drawMode === TriangleFanDrawMode) {
    // gl.TRIANGLE_FAN

    for (let i = 1; i <= numberOfTriangles; i++) {
      newIndices.push(index.getX(0));
      newIndices.push(index.getX(i));
      newIndices.push(index.getX(i + 1));
    }
  } else {
    // gl.TRIANGLE_STRIP

    for (let i = 0; i < numberOfTriangles; i++) {
      if (i % 2 === 0) {
        newIndices.push(index.getX(i));
        newIndices.push(index.getX(i + 1));
        newIndices.push(index.getX(i + 2));
      } else {
        newIndices.push(index.getX(i + 2));
        newIndices.push(index.getX(i + 1));
        newIndices.push(index.getX(i));
      }
    }
  }

  if (newIndices.length / 3 !== numberOfTriangles) {
    console.error(
      "THREE.GLTFLoader.toTrianglesDrawMode(): Unable to generate correct amount of triangles."
    );
  }

  // build final geometry

  const newGeometry = geometry.clone();
  newGeometry.setIndex(newIndices);

  return newGeometry;
}

export { GLTFLoader };
